1. Field of the Invention
The invention relates to wrapping a load with packaging material, and, more particularly, to stretch wrapping.
2. Description of the Prior Art
Various packaging techniques have been used to build a load of unit products and subsequently wrap them for transportation, storage, containment and stabilization, protection and waterproofing. One system uses stretch wrapping machines to stretch, dispense, and wrap stretch packaging material around a load. Stretch wrapping can be performed as an inline automated packaging technique which dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Pallet stretch wrapping, whether accomplished by turntable, rotating arm, or rotating ring typically covers the four vertical sides of the load with a stretchable film such as polyethylene film. In each of these arrangements, relative rotation is provided between the load and a packaging material dispenser to wrap packaging material about the sides of the load.
Conventionally, fork trucks were used to deliver loads to and remove loads from a wrapping area. The fork truck would bring an unwrapped load to a wrapping area, set the unwrapped load aside, remove a wrapped load from a wrapping station and set it aside, place the unwrapped load on the wrapping station, initiate the wrapping sequence, and pick up and remove the wrapped load from the wrapping area. Such a process requires multiple handling of each load, a large amount of maneuvering on the part of the fork truck, and requires the fork truck driver to exit the fork truck in order to initiate the wrapping sequence. Alternatively, more than one fork truck was used to deliver and remove the loads from the wrapping station. However, use of more than one truck led to inefficiency.
Conveyorized wrapping apparatus have been used to reduce fork truck usage during the wrapping process. Powered conveyors may be used to deliver and remove a load from a wrapping station. Such powered conveyors require a large amount of space and are expensive to build and maintain. Powered conveyors mounted on turntables have been used to eliminate multiple handling of the load. However, such devices are mechanically complex and therefore are costly to maintain. In addition, such devices generally require an electrical or pneumatic transfer device under the turntable to effectuate transfer from the wrapping station, which increases the cost and complexity of the device. Dual turntables without conveyors have also been used to provide dual wrapping stations, however, problems with material handling interfaces and synchronizing of the infeed and outfeed flow exist. Finally, non-powered conveyors on turntables have been used, but such conveyors require the operator to push the load along the conveyor surface, leading to safety and stress problems.
In light of these drawbacks, there is a need to move the load to and from a wrapping station in a simple, reliable, and inexpensive manner.